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Donald Trump's field director resigns

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A shakeup atop Donald Trump's campaign has insiders questioning the role of Campaign Manager Corey Lewandowski

Paul Manafort's arrival has in part diminished Lewandowski's once outsized presence

New York (CNN)With Donald Trump's recent hiring of seasoned Republican operatives who are taking on an expanding role within the GOP front-runner's campaign, a common question keeps coming up: What happens to Corey Lewandowski?

Asked by reporters as he was casting his ballot in the New York primary, Trump said the reorganization of his campaign is going "very smooth."

But sources familiar with Trump's staff shakeup tell CNN campaign manager Lewandowski's role is no longer as clearly defined.

"They sort of have to figure out what Corey's role is," one campaign adviser said. "Corey has just never run a national campaign before."

Trump's decision to bring on Paul Manafort, a longtime Republican adviser dating back to Ford's 1976 campaign, to lead the real estate tycoon's convention and delegate efforts, has in part diminished Lewandowski's once outsized presence within the campaign as Trump seeks to notch not just primary night wins but amass the necessary delegates to secure the nomination.

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As part of the Trump's new "bifurcated campaign," Lewandowski is evolving into more of a traveling "chief of staff" for the campaign, one source said, while Manafort has become a combination of "secretary of defense and secretary of state."

Another source explained Lewandowski will continue his current role planning campaign events and will be a key adviser to Trump as they travel in the ongoing campaign.

"Trump needed the expertise on managing delegates and conventions. That's why Paul came in," said one source.

"I brought in Paul Manafort who's a total professional, won tremendous numbers of races. Corey's done an excellent job. Everybody seems to be getting along pretty well," Trump said Tuesday morning on "Fox and Friends."

Sources familiar with Trump's recent moves said Manafort's ascent inside Trump world, along with the hiring of former Scott Walker Campaign Manager Rick Wiley and Washington-based attorney William McGinley, signal a shift in the Republican front-runner's calculus that he must calm the nerves of jittery party insiders.

A source familiar with Trump's intensified delegate efforts said GOP regulars can stomach Trump's unorthodox style and anti-establsihment message. But they want to see Trump show more campaign competence as well.

"It's not enough to be anti-establishment," said one of Trump's more seasoned delegate operatives. "But you have to show that you know what you are doing."

Lewandowski's sphere of influence within the campaign is also shrinking amid the staff shakeup.

Stuart Jolly, the campaign's national field director and a longtime Lewandowski loyalist, resigned Monday, less than a week after Trump hired Wiley as national political director -- a position that would have made Jolly his subordinate.

Jolly, who's run the campaign's ground operations for months alongside Lewandowski and deputy campaign manager Michael Glassner, told CNN Monday that he "wasn't pushed" out, but that "you gotta love and respect the people you work for."

Jolly's decision to leave came after senior campaign staff met Saturday to formalize Manafort and Wiley's expanded roles, with Trump handing the two men broad authority to devise the campaign's strategy in upcoming contests, Jolly and two Trump campaign sources familiar with the Saturday meeting told CNN.

Trump and his newly revamped team of top advisers will have the opportunity to demonstrate their enhanced strategic skills in the coming weeks, as the New York billionaire closes in on the magic number of 1,237 delegates needed to clinch the nomination.

A delegate adviser to team Trump said the campaign's Washington office will soon begin micro-targeting uncommitted delegates, with the hopes of convincing those soon to be in-demand party regulars that the GOP front-runner understands their individual concerns.

Those delegates should not expect wining and dining or free flights on Trump's plane. Trump has ruled that out. But his delegate team hopes to arrange sit-down meetings with individual delegates to make the candidate's case.

Top Trump officials are confident they can win the nomination on the first ballot. But if they fall short, winning over those uncommitted delegates will be critical at July's GOP convention in Cleveland.

As for Lewandowski, a source familiar with the campaign's inner workings noted Trump's feisty campaign manager still has the support within the organization where it counts, with the candidate himself. That loyalty was on display just last week as Lewandowski was cleared of a charge of battery after he allegedly grabbed a reporter's arm at a campaign event. Trump again insisted Lewandowski did nothing wrong.

"I am sure Corey will be fine and doing more of what he loves which is on site (at campaign events)," one Trump source said. "Mr. Trump is extremely loyal to him."